Homoleptic, heteroleptic and mixed-valent thallium and indium complexes of multidentate chalcogen-centred PCP-bridged ligands

摘要

The metathetical reaction of [Li(TMEDA)][HC(PPh_2Se)_2] ([Li(TMEDA)]1) with TlOEt in a 1:1 molar ratio afforded a homoleptic Tl(i) complex as an adduct with LiOEt, Tl[HC(PPh_2Se)_2] ·LiOEt (7), which undergoes selenium-proton exchange upon mild heating (60 °C) to give the mixed-valent Tl(i)/Tl(iii) complex {[Tl][Tl{(Se) C(PPh_2Se)_2}_2]}_∞ (8). Treatment of TlOEt with [Li(TMEDA)]_2[(SPh_2P) _2CE′E′C(PPh_2S)_2] (3b, E′ = S; 3c, E′ = Se) in a 2:1 molar ratio produced the binuclear Tl(i)/Tl(i) complexes Tl_2[(SPh_2P)_2CE′E′ C(PPh_2S)_2] (9b, E′ = S; 9c, E′ = Se), respectively. Selenium-proton exchange also occurred upon addition of [Li(TMEDA)]1 to InCl_3 to yield the heteroleptic complex (TMEDA)InCl[(Se)C(PPh_2Se)_2] (10a). Other examples of this class of In(iii) complex, (TMEDA)InCl[(E′)C(PPh_2E)_2] (10b, E = E′ = S; 10c, E = S, E′ = Se) were obtained via metathesis of InCl_3 with [Li(TMEDA)]_2[(E′)C(PPh _2E)_2] (2b, E = E′ = S; 2c, E = S, E′ = Se, respectively). All new compounds have been characterized in solution by ~1H and ~(31)P NMR spectroscopy and the solid-state structures have been determined for 8, 9c and 10a-c by single-crystal X-ray crystallography. Complex 8 is comprised of Tl~+ ions that are weakly coordinated to octahedral [Tl{(Se)C(PPh_2Se)_2} _2]~- anions to give a one-dimensional polymer. The complex 9c is comprised of two four-coordinate Tl~+ ions that are each S,S′,S′′,Se bonded to the hexadentate [(SPh_2P) _2CSeSeC(PPh_2S)_2]~(2-) ligand in which d(Se-Se) = 2.531(2) ?. The six-coordinate In(iii) centres in the distorted octahedral complexes 10a-c are connected to a tridentate [(E′)C(PPh _2E)_2]~(2-) dianion, a chloride ion and a neutral bidentate TMEDA ligand.